1. Field of the Invention
This invention pertains generally to high frequency detection and control, and more particularly to THz modulation with metamaterials.
2. Description of Related Art
Substantial research is being performed on metamaterials used for microwave radiation, and is in part due to the ease of fabrication of sub-wavelength structures at these frequencies. Indeed, negative refractive index media composed of negative permittivity (∈1<0) and negative permeability (μ1<0) metamaterial elements was first demonstrated at microwave frequencies. As a result intense theoretical, computational and experimental studies of exotic phenomena have arisen, such as perfect lensing and cloaking. Recently, researchers have ventured to create functional metamaterials at near-infrared and visible frequencies. Considerably less work has been directed in the THz frequencies, although the design flexibility associated with metamaterials may prove promising from a device perspective in filling the THz gap.
Metamaterials are geometrically scalable, which translates to operability over many decades of frequency. This engineering tunability is in fact a distinguishing and advantageous property of these materials. However, for many applications it is desirable to have real-time tunability. For instance, short-range wireless THz communication or ultrafast THz interconnects require switches and modulators. Current state-of-the-art THz modulators based on semiconducting structures have the desirable property of being broadband, which is of relevance to THz interconnects. However, these semiconducting structures are only capable of a few percent modulation and usually require cryogenic temperatures. Therefore, further improvement in the performance characteristics of these devices is required before practical application can be made of them.
Accordingly a need exists for apparatus and methods of performing switching and modulation at THz frequencies, including amplitude modulation of narrowband devices, for example THz quantum cascade lasers, thus enabling near-term practical applications. These needs and others are met within the present invention, which overcomes the deficiencies of previously developed apparatus and methods of THz generation and control.